New fire at Japanese nuke building with spent fuel

Unit 4 again ablaze after fire that left 2 workers missing; Units 5, 6 also eyed

SOMA, Japan — The world's worst nuclear crisis since Chernobyl rose to a new level Wednesday as another fire erupted at Japan's stricken nuclear complex and engineers worried about the possibility of blasts at two other reactors. In addition, two workers were reported missing after an earlier fire.

1. Japan earthquake
   1. New fire at nuke building with spent fuel
   2. Millions in Japan struggle without electricity, heat
   3. Panic grips Tokyo as radiation levels rise
   4. Japan radioactivity could enter food chain
   5. Woman, 70, found alive 4 days after tsunami
   6. 
       Officials closely monitor Japan’s weather
   7. 
      Time-lapse of  aftershocks
   8. 
       Images of chaos, destruction

The new fire broke out Wednesday morning at Unit 4 of the Fukushima Dai-ichi plant. A blast and fire at Unit 4 nearly 24 hours earlier opened a hole in the outer building, emitting radiation from overheating spent fuel in a storage pool.

Two workers inside the unit were missing after the first fire, Japan's nuclear safety agency said.

Officials were also concerned about Units 5 and 6.

"Plant operators were considering the removal of panels from units 5 and 6 reactor buildings to prevent a possible buildup of hydrogen," the International Atomic Energy Agency said in a statement.

"It was a buildup of hydrogen at units 1, 2, and 3 that led to explosions at the Dai-ichi facilities in recent days," it added.

Units 5 and 6 were loaded with nuclear fuel but not producing when Friday's quake and tsunami struck. They had been considered stable, but on Tuesday a senior Japanese official said temperatures there were also slightly elevated.

"The power for cooling is not working well and the temperature is gradually rising, so it is necessary to control it," Chief Cabinet Secretary Yukio Edano told reporters.

Japanese officials told the IAEA that the spent fuel storage area had caught fire and that radioactivity was "being released directly into the atmosphere."

After the first Unit 4 fire was extinguished, a Japanese official said the pool used to cool the spent fuel rods might still be boiling, though the reported levels of radiation had dropped dramatically by evening.

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Experts noted that much of the leaking radiation was apparently in steam from boiling water. It had not been emitted directly by fuel rods, which would be far more virulent, they said.

"It's not good, but I don't think it's a disaster," said Steve Crossley, an Australia-based radiation physicist.

The fuel rods are encased in safety containers meant to prevent them from resuming nuclear reactions, nuclear officials said. But they acknowledged that there could have been damage to the containers.

Tuesday night, Japan ordered the plant operator, Tokyo Electric Power, to inject water into the pool "as soon as possible to avert a major nuclear disaster."

Officials initially thought about using helicopters to dump water on the pool building, but that was later deemed impractical. Other options were under consideration, including fire engines.The IAEA also said Tuesday that an explosion Monday at the plant, this one within Unit 2, "may have affected the integrity of its primary containment vessel." That means radioactivity could be leaking from the containment vessel.

Japanese Prime Minister Naoto Kan said low levels of radiation had spread from the complex along Japan's northeastern coast.

"The possibility of further radioactive leakage is heightening," a grim-faced Kan said in an address to the nation.

Levels of 400 millisieverts per hour had been recorded near unit 4, the government said. Exposure to over 100 millisieverts a year is a level which can lead to cancer, according to the World Nuclear Association.

The radiation releases prompted Japan on Tuesday to order 140,000 people to seal themselves indoors and a 30-kilometer (19-mile) no-fly zone was imposed around the site for commercial traffic.

Weather forecasts for the Fukushima area were for snow and wind Tuesday evening, blowing southwest toward Tokyo, then shifting and blowing east out to sea. That's important because it shows which direction a possible nuclear cloud might blow.

'Clearly in a catastrophe'
Soon after the latest events, France's nuclear safety authority ASN said the disaster ranks as a level 6 on the international scale of 1 to 7.

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Level 7 was used only once, for Chernobyl in Ukraine in 1986. The 1979 accident at the Three Mile Island nuclear power plant in Pennsylvania was rated a level 5.

"It is very clear that we are at a level 6," ASN President Andre-Claude Lacoste told a news conference in Paris. "We are clearly in a catastrophe."

"Right now it's worse than Three Mile Island" but it's nowhere near the levels of radioactivity released during Chernobyl, added Donald Olander, a professor emeritus of nuclear engineering at the University of California at Berkeley.

At Three Mile Island, the radiation leak was held inside the containment shell — thick concrete armor around the reactor. The Chernobyl reactor had no shell and was also operational when the disaster struck. The Japanese reactors automatically shut down when the quake hit.

The IAEA said about 150 people in Japan had received monitoring for radiation levels and that measures to "decontaminate" 23 of them had been taken.

Clearing up nuclear questions

Though Japanese officials urged calm, Tuesday's developments fueled a growing panic amid widespread uncertainty over what would happen next.

In the worst-case scenario, one or more reactor cores would completely melt down, a disaster that would spew large amounts of radioactivity into the atmosphere.

 Video: At least 15,000 people missing in Japan (on this page)

Officials in Tokyo — 150 miles to the south of the plant — said radiation in the capital was 10 times normal by evening but there was no threat to human health.

How much radiation is dangerous?

1. Radiation is measured using the unit sievert, which quantifies the amount of radiation absorbed by human tissues. One sievert is 1,000 millisieverts (mSv). One millisievert is 1,000 microsieverts.

   The average person in the United States is exposed to about 6.2 millisieverts a year, mostly from background radiation and medical tests.

   Some facts about radiation exposure:

   • A person would need to be exposed to at least 100 mSv a year to have an increase in cancer risk. Exposure to 1,000 mSv (1 sievert) over a year would probably cause a fatal cancer many years later in five out of every 100 people who receive that much radiation.
   • A total body CT scan exposes a person to about 10 mSv.
   • A mammogram exposes a woman to about 0.7 mSv.
   • CT colonography is about 5 to 8 mSv.
   • A CT heart scan is about 12 mSv.
   • A typical chest X-ray involves exposure of about 0.02 mSv
   • A dental X-ray can be 0.01 mSv.
   • Coast-to-coast airplane flight exposes a person to about .03 mSv. Airline crews flying the New York-Tokyo polar route are exposed to 9 mSv a year.

   Sources: Reuters; New England Journal of Medicine; American Cancer Society; World Nuclear Association and Taiwan's Atomic Energy Council

Closer to the stricken nuclear complex, the streets in the coastal city of Soma were empty as the few residents who remained there heeded the government's warning to stay indoors.

Interactive: How a nuclear plant works

Officials just south of Fukushima reported up to 100 times the normal levels of radiation Tuesday morning. While those figures are worrying if there is prolonged exposure, they are far from fatal.

Officials warned there is danger of more leaks and told people living within 19 miles of the Dai-ichi complex to stay indoors.

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"Please do not go outside. Please stay indoors. Please close windows and make your homes airtight," Edano told residents in the danger zone.

"These are figures that potentially affect health. There is no mistake about that," he said.

Some 70,000 people had already been evacuated from a 12-mile radius from the Dai-ichi complex. About 140,000 are in the new warning zone.

Friday's 9.0-magnitude earthquake and the ensuing tsunami have killed more than 10,000 people.

70 workers at plant Workers were desperately trying to stabilize the three reactors at Units 1, 2 and 3 that were working when the quake and tsunami struck. Releases of hydrogen gas caused explosions that destroyed the outer structures at each unit.

Fourteen pumps have been brought in to get seawater into those three reactors.

There was also possible core damage at the Unit 2 reactor, estimated at less than 5 percent of the fuel, and there might also be damage to the unit's primary containment structure.

"Is it a crack? Is it a hole? Is it nothing? That we don't know yet," IAEA chief Yukiya Amano told reporters.

But he said the pressure in the containment vessel had not fallen. "If there is a huge damage the pressure should go down."

Unit 4, where the pool is, had been under maintenance and was not operating at the time of the quake and tsunami.

With power out and the regular coolant gone, engineers are now injecting seawater into the reactors as a last-ditch coolant. Tokyo Electric Power Co., which operates the plant, said it would try to inject seawater inside the pool area within three days.

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Officials said 70 workers were at the complex, struggling with its myriad problems. The workers, all of them wearing protective gear, are being rotated in and out of the danger zone quickly to reduce their radiation exposure.

About 800 other staff were evacuated. The fires and explosions at the reactors have injured 15 workers and military personnel.

Prime Minister Kan himself lambasted TEPCO for taking so long to inform his office about one of the blasts, Kyodo news service reported.

"The TV reported an explosion. But nothing was said to the premier's office for about an hour," a Kyodo reporter quoted Kan as telling power company executives. "What the hell is going on?"

The death toll from last week's earthquake and tsunami jumped as police confirmed the number killed had topped 2,400. Officials say that at least 10,000 people may have died in Miyagi province alone, but those deaths are not confirmed.

Story: Millions in Japanese cold struggle without electricity, heat

The Dai-ichi plant is the most severely affected of three nuclear complexes that were declared emergencies after suffering damage in Friday's quake and tsunami, raising questions about the safety of such plants in coastal areas near fault lines and adding to global jitters over the industry.

The Fukushima Dai-ichi complex was due to be decommissioned in February but was given a new 10-year lease on life.

Its reactors were designed by General Electric. (Msnbc.com is a joint venture between NBC Universal and Microsoft. GE is a part owner of NBC Universal.)

Japan has a total of 55 reactors spread across 17 complexes nationwide.

GE-designed reactors in Fukushima have 23 sisters in U.S.

The impact of the earthquake and tsunami dragged down stock markets. The benchmark Nikkei 225 stock average plunged for a second day Tuesday, nose-diving more than 10 percent to close at 8,605.15 while the broader Topix lost more than 8 percent.

To lessen the damage, Japan's central bank made two cash injections totaling $98 billion Tuesday into the money markets after pumping in $184 billion on Monday.

Initial estimates put repair costs in the tens of billions of dollars, costs that would likely add to a massive public debt that, at 200 percent of gross domestic product, is the biggest among industrialized nations.

The Associated Press and Reuters contributed to this report.